In some environments, overhead roll-up door assemblies, and in particular the door panels in the assemblies, are required to withstand great amounts of force and pressure resulting from environmental causes. For example, large differences or variations in air pressure on opposing sides of overhead roll-up door panels, or high winds directed at one side of a door panel, may cause a significant force to be imparted on one side of the door panel. In door assemblies which have large door panels, thousands of pounds of force due to wind and/or air pressure may be imparted on the door. These large forces may cause the door panel to unwantedly disengage from the door assembly and any side columns or guide tracks in which a portion of the door is positioned for travel, through the gap or opening which allows for the side columns to engage the door panel. Disengagement of the door panel may cause damage to the door and surrounding structures, may cause injuries to individuals proximate the door panel, and may prevent the door from properly operating and/or properly opening and blocking or closing the opening proximate the door.
Wind locks are an effective technique for keeping a flexible overhead roll-up door panel engaged within vertical side columns and guide tracks in high speed overhead roll-up door assemblies. There are different types of “wind locks” known within the industry, like, for example, rollers, buttons, and knobs. However, buttons and knobs, for example, fail to hold up to very large wind loads when used with large doors, or in the face of high winds or air pressure differentials as they tend to break off the door panel. Therefore, under these conditions, it is common to use a thick strip of rubber along the continuous vertical edges of the door panel to hold it within the side columns and guide tracks and prevent the door panel from “blowing out” while under a wind load.
Because the door panel and wind locks move vertically within and may engage the side columns as the door is opening and closing, it is desirable to move the door panel while generating as little friction as possible. Low friction between the wind locks and side columns permits a lower-powered HP motor to lift the door panel, and also allows the door panel to close completely (the door typically closes under its own weight) without stalling or binding up as the door panel is lowered in higher wind loads or greater air pressure differentials. Therefore, it is also common for the industry to overlap a thick rubber or similar wind lock with a low-friction fabric polyethylene terephthalate (PET) material, or the like.
In addition to combating wind loads, flexible overhead roll-up door panels must also be able to disengage when impacted with a transverse force by an object or vehicle passing proximate or through the door. Ideally, the door panels are capable of disengaging after impact without damaging the door assembly (panel, wind locks, side columns, motor) or any surrounding structures. In order to avoid such damage, it is common in the industry to use a 45 degree (or similarly angled) beveled inner surface on the wind lock and a mating 45 degree angled (or similarly complementary angled) engagement surface on the side column where the wind lock may engage or contact the side column with the door panel extending through a gap in the side column proximate the angled, mating surface. Utilizing a gap and mating angles may create a “wedge” effect as a portion or more the wind lock is pulled into and potentially through the gap in the side column. The wedge effect may allow the wind lock to compress and more easily slide or fit through a gap in the side column and “open” or expand the gap in the side column to allow the door panel to escape, instead of simply being pulled against the side column resulting in either the wind lock being ripped off, the panel being torn, or the side columns being bent or damaged during impact. The combination of the complementary angled faces on the wind lock and side column may also act to move or flex or rotate a portion of the side column to expand the gap in the side column to more easily allow the wind lock and door panel to escape. While this effect is desirable if the door panel is impacted or hit by an object, it is undesirable in response to a wind load being applied to the door panel.
Using continuous mating angles along the entirety of the door panel has a disadvantage—it may increase the friction between the wind lock and side column when the door is opening or closing. Under wind loads or when an air pressure differential exists, the door panel may “bow out.” The bowing of the door panel may pull the wind locks inward, towards the center of the opening or door panel, causing the wind locks to engage the side columns, or more problematically become wedged in the side column gaps, as the door panel is opening or closing. For example, the mating angled surfaces of the wind locks and side columns can result in the overall increase in friction. This may create wear on the wind locks, door panel, and side columns, and puts unwanted stress on the motor controlling the operation of the door panel. When under a high wind load, these wind locks may also become stuck in the gap and side column, causing the door panel to stick, potentially damaging the door panel, the wind locks, and the motor.
Therefore, it would be advantageous to design a wind lock, door panel, side column and overall door assembly which eliminates the use of continuous mating 45 degree or similarly complementary angles in the wind lock and side column to substantially lower friction and enhance satisfactory wind load response, while at the same time maintaining or enhancing a satisfactory wind load response and the disengageability of the door panel if the door panel is impacted with a transverse force.
The present invention is provided to solve these and other problems.